In general, among technologies to form various thin films on a substrate or a wafer, a CVD (Chemical Vapor Deposition) scheme has been extensively used. The CVD scheme results in a chemical reaction. According to the CVD scheme, a semiconductor thin film or an insulating layer is formed on a wafer surface by using the chemical reaction of a source material.
The CVD scheme and the CVD device have been spotlighted as an important thin film forming technology due to the fineness of the semiconductor device and the development of high-power and high-efficiency LED. Recently, the CVD scheme has been used to deposit various thin films, such as a silicon layer, an oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a tungsten layer, on a wafer. In addition, studies and researches on a wafer having a large diameter have been continuously performed in order to reduce the manufacturing cost.
However, the CVD scheme, which has been recently employed, has difficulty in providing uniform temperature distribution when increasing the size of a susceptor or a hot plate. Accordingly, depositing an epitaxial layer on a substrate or a wafer having the size of 6″ or more under development may be difficult.
In a susceptor employed in the conventional CVD scheme, after providing a wafer or a substrate on a hot plate, various thin films are deposited on the wafer or the substrate. In this case, the hot plate may include a material having resistance against a high temperature. A hot plate used in the deposition of silicon carbide (SiC) may mainly include SiC. The SiC has a conductor representing the thermal conductivity of 300 W/mK.
However, as the wafer is manufactured with a large diameter, the hot plate is enlarged, so that heat may not be uniformly transferred on the wafer. Therefore, the thin film is irregularly deposited on the wafer, so that the characteristic of the thin film may be degraded.
Referring to a reference “Pernot, G., et al. Precise control of thermal conductivity at the nanoscale through individual phonon-scattering barriers. Nat Mater 9, 491-495 (2010).”, the reference discloses the coating of Si/Ge in multiple layers including nano-size single layers.
If the material is coated in a nano-size, thermal conductivity is significantly reduced as compared with bulk silicon. In other words, the thermal conductivity of the nano-size material is significantly lower than that of the bulk material.
Accordingly, even if a bulk material is the same as the nano-size material, the bulk material and the nano-size material make difference in the thermal conductivity due to the size effect.
Therefore, the hot plate according to the present embodiment aims at fabricating a hot plate capable of uniformly distributing temperature on the wafer by using the difference in the thermal conductivity caused by the size effect.